Skis used especially in alpine skiing are constituted by an elongated beam ending, at the front, in a tip, and, at the rear, in a heel-piece. The thickness of the ski is generally greater in the central portion, and gradually diminishes toward the ends, so that the ski forms, as it were, a beam exhibiting specialized flection.
Present-day skis normally have a composite structure, in which different materials are combined so that each of them comes optimally into play, given the distribution of the mechanical stresses generated when the ski is used. Thus, the structure generally comprises peripheral protective elements, internal strengthening elements designed to withstand flectional and torsional stresses, and a core, as well as sliding and attachment components. These elements are assembled by adhesive bonding or injection, and assembly generally takes place under heat in a mold having the final shape of the ski, comprising a front portion raised in pronounced fashion to form a tip, a rear portion slightly raised to form a heel-piece, and a cambered central part.
Despite the manufacturers' interest in producing quality skis, they have not, to date, produced a high-performance ski which proves satisfactory under all conditions of use.
It is known that the size and structural characteristics of the ski determine the characteristics allowing good performance, its dimension line making it possible to maneuver the ski in turns while promoting its strength under curvature, and its thickness line permitting proper adjustments under flection. The edge line allows adjustment of torsion.
French Patent Publication No. 2 522 978 discloses the use of a ski whose lateral faces are inclined uniformly or variably, in order to reduce lateral friction during the execution of turns. Such inclination is variable, in particular, to allow adaptation to variations in width of the upper surface of the ski, occurring in the direction of a curvilinear narrowing in the area of the central zone. In the area of the bindings, the width may be uniform, as shown in FIG. 1 of the patent so as to create a platform capable of receiving the bindings. This ski shape requires a complex manufacturing process, because of the fact that the upper edges are curvilinear over a large part of the ski length. This problem arises, in particular, in modern ski structures utilizing pre-impregnated fibrous reinforcement pieces, since bending in the area of the edges is difficult and the fibers cannot be arranged evenly in the area of these upper edges. As a result, edges are weaker mechanically. Furthermore, the non-rectilinear edges of the upper face do not provide simple, effective markings for decoration of the upper face using sublimation means, for example.
Applicant's French Patent No. 2 598 930 concerns a ski whose upper platform has a constant width over the entire length of the ski and whose edges have variable inclination allowing adaptation to the variations in width of the sliding surface, or dimension line, of the ski. This type of ski has a number of advantages prior art skis, yet is not completely satisfactory for some grades of snow and kinds of skiers, for whom skiing requires a number of further improvements.